1. Field of the Invention
The invention relates to a height-adjustable implant for insertion between vertebral bodies and a tool suitable for the manipulation thereof.
2. Present State of the Art
An implant known from patent specification DE 196 22 827 A1, for example, has a first and a second sleeve part, which second sleeve part has an external thread which is placed in the first sleeve part by means of a longitudinal portion so as to be prevented from rotating and axially displaceable whilst its longitudinal portion projecting out from the first sleeve part is enclosed by a nut engaging in the external thread. When the nut is rotated, the second sleeve part is moved out of the first sleeve part. In order to operate the nut, a rod-shaped manipulating tool is inserted by its free end in a recess on the external circumference of the nut. By pivoting the tool in a plane extending transversely to the longitudinal axis of the implant, the nut is turned by a further distance corresponding to the pivot angle of the tool. The tool is then extracted from the nut and the process described above is repeated until the implant is at the requisite height. During the operation of turning the nut, the first sleeve part must not turn as well and as a rule, it therefore has to be held still by means of another tool. The height adjustment of the known implant therefore requires extra time and technical equipment. Furthermore, a relatively large orifice is needed for the operation in order to perform the described manipulations unobstructed.